The present invention relates to a sensing apparatus including a sensing bridge circuit for generating a sensor signal having the voltage level representing a detected physical quantity and a temperature detecting bridge circuit for correcting the temperature characteristics of the sensing bridge circuit.
For example, a conventional pressure sensing apparatus includes a diaphragm and a gauge resistor formed on a semiconductor chip. In this kind of conventional pressure sensing apparatus, the temperature compensation for adjusting the sensitivity or the offset is usually performed through an analog correcting circuit. Numerous operational amplifiers are required. In general, downsizing the operational amplifier is difficult. In other words, the conventional sensing apparatus relying on the operational amplifiers needs to prepare a semiconductor chip having a large chip area, and therefore cannot reduce the overall size.
Furthermore, due to the aging phenomenon which reduces the stress of the protective film covering the chip surface, the offset of each operational amplifier may deviate from its initial value or the pair ratio of resistors associated with each operational amplifier may also deviate from its initial value. In such cases, it is difficult to prevent the circuit constants of each section from variously changing or fluctuating. As a result, the sensing accuracy of the finally obtained pressure value is deteriorated.